xen: switch extra memory accounting to use pfns

Instead of using physical addresses for accounting of extra memory
areas available for ballooning switch to pfns as this is much less
error prone regarding partial pages.

Reported-by: Roger Pau Monné <roger.pau@citrix.com>
Tested-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 70de4c8b8f271dbfeeb9f593455b08d2550f6e16..f5ef6746d47a0ee36f6b0a11edd0c49cbcf3590a 100644 (file)
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -90,62 +90,69 @@ static void __init xen_parse_512gb(void)
        xen_512gb_limit = val;
 }
 
-static void __init xen_add_extra_mem(phys_addr_t start, phys_addr_t size)
+static void __init xen_add_extra_mem(unsigned long start_pfn,
+                                    unsigned long n_pfns)
 {
        int i;
 
+       /*
+        * No need to check for zero size, should happen rarely and will only
+        * write a new entry regarded to be unused due to zero size.
+        */
        for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
                /* Add new region. */
-               if (xen_extra_mem[i].size == 0) {
-                       xen_extra_mem[i].start = start;
-                       xen_extra_mem[i].size  = size;
+               if (xen_extra_mem[i].n_pfns == 0) {
+                       xen_extra_mem[i].start_pfn = start_pfn;
+                       xen_extra_mem[i].n_pfns = n_pfns;
                        break;
                }
                /* Append to existing region. */
-               if (xen_extra_mem[i].start + xen_extra_mem[i].size == start) {
-                       xen_extra_mem[i].size += size;
+               if (xen_extra_mem[i].start_pfn + xen_extra_mem[i].n_pfns ==
+                   start_pfn) {
+                       xen_extra_mem[i].n_pfns += n_pfns;
                        break;
                }
        }
        if (i == XEN_EXTRA_MEM_MAX_REGIONS)
                printk(KERN_WARNING "Warning: not enough extra memory regions\n");
 
-       memblock_reserve(start, size);
+       memblock_reserve(PFN_PHYS(start_pfn), PFN_PHYS(n_pfns));
 }
 
-static void __init xen_del_extra_mem(phys_addr_t start, phys_addr_t size)
+static void __init xen_del_extra_mem(unsigned long start_pfn,
+                                    unsigned long n_pfns)
 {
        int i;
-       phys_addr_t start_r, size_r;
+       unsigned long start_r, size_r;
 
        for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
-               start_r = xen_extra_mem[i].start;
-               size_r = xen_extra_mem[i].size;
+               start_r = xen_extra_mem[i].start_pfn;
+               size_r = xen_extra_mem[i].n_pfns;
 
                /* Start of region. */
-               if (start_r == start) {
-                       BUG_ON(size > size_r);
-                       xen_extra_mem[i].start += size;
-                       xen_extra_mem[i].size -= size;
+               if (start_r == start_pfn) {
+                       BUG_ON(n_pfns > size_r);
+                       xen_extra_mem[i].start_pfn += n_pfns;
+                       xen_extra_mem[i].n_pfns -= n_pfns;
                        break;
                }
                /* End of region. */
-               if (start_r + size_r == start + size) {
-                       BUG_ON(size > size_r);
-                       xen_extra_mem[i].size -= size;
+               if (start_r + size_r == start_pfn + n_pfns) {
+                       BUG_ON(n_pfns > size_r);
+                       xen_extra_mem[i].n_pfns -= n_pfns;
                        break;
                }
                /* Mid of region. */
-               if (start > start_r && start < start_r + size_r) {
-                       BUG_ON(start + size > start_r + size_r);
-                       xen_extra_mem[i].size = start - start_r;
+               if (start_pfn > start_r && start_pfn < start_r + size_r) {
+                       BUG_ON(start_pfn + n_pfns > start_r + size_r);
+                       xen_extra_mem[i].n_pfns = start_pfn - start_r;
                        /* Calling memblock_reserve() again is okay. */
-                       xen_add_extra_mem(start + size, start_r + size_r -
-                                         (start + size));
+                       xen_add_extra_mem(start_pfn + n_pfns, start_r + size_r -
+                                         (start_pfn + n_pfns));
                        break;
                }
        }
-       memblock_free(start, size);
+       memblock_free(PFN_PHYS(start_pfn), PFN_PHYS(n_pfns));
 }
 
 /*
@@ -156,11 +163,10 @@ static void __init xen_del_extra_mem(phys_addr_t start, phys_addr_t size)
 unsigned long __ref xen_chk_extra_mem(unsigned long pfn)
 {
        int i;
-       phys_addr_t addr = PFN_PHYS(pfn);
 
        for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
-               if (addr >= xen_extra_mem[i].start &&
-                   addr < xen_extra_mem[i].start + xen_extra_mem[i].size)
+               if (pfn >= xen_extra_mem[i].start_pfn &&
+                   pfn < xen_extra_mem[i].start_pfn + xen_extra_mem[i].n_pfns)
                        return INVALID_P2M_ENTRY;
        }
 
@@ -176,10 +182,10 @@ void __init xen_inv_extra_mem(void)
        int i;
 
        for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
-               if (!xen_extra_mem[i].size)
+               if (!xen_extra_mem[i].n_pfns)
                        continue;
-               pfn_s = PFN_DOWN(xen_extra_mem[i].start);
-               pfn_e = PFN_UP(xen_extra_mem[i].start + xen_extra_mem[i].size);
+               pfn_s = xen_extra_mem[i].start_pfn;
+               pfn_e = pfn_s + xen_extra_mem[i].n_pfns;
                for (pfn = pfn_s; pfn < pfn_e; pfn++)
                        set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
        }
@@ -507,7 +513,7 @@ void __init xen_remap_memory(void)
                } else if (pfn_s + len == xen_remap_buf.target_pfn) {
                        len += xen_remap_buf.size;
                } else {
-                       xen_del_extra_mem(PFN_PHYS(pfn_s), PFN_PHYS(len));
+                       xen_del_extra_mem(pfn_s, len);
                        pfn_s = xen_remap_buf.target_pfn;
                        len = xen_remap_buf.size;
                }
@@ -517,7 +523,7 @@ void __init xen_remap_memory(void)
        }
 
        if (pfn_s != ~0UL && len)
-               xen_del_extra_mem(PFN_PHYS(pfn_s), PFN_PHYS(len));
+               xen_del_extra_mem(pfn_s, len);
 
        set_pte_mfn(buf, mfn_save, PAGE_KERNEL);
 
@@ -744,7 +750,7 @@ static void __init xen_reserve_xen_mfnlist(void)
  **/
 char * __init xen_memory_setup(void)
 {
-       unsigned long max_pfn;
+       unsigned long max_pfn, pfn_s, n_pfns;
        phys_addr_t mem_end, addr, size, chunk_size;
        u32 type;
        int rc;
@@ -831,9 +837,11 @@ char * __init xen_memory_setup(void)
                                chunk_size = min(size, mem_end - addr);
                        } else if (extra_pages) {
                                chunk_size = min(size, PFN_PHYS(extra_pages));
-                               extra_pages -= PFN_DOWN(chunk_size);
-                               xen_add_extra_mem(addr, chunk_size);
-                               xen_max_p2m_pfn = PFN_DOWN(addr + chunk_size);
+                               pfn_s = PFN_UP(addr);
+                               n_pfns = PFN_DOWN(addr + chunk_size) - pfn_s;
+                               extra_pages -= n_pfns;
+                               xen_add_extra_mem(pfn_s, n_pfns);
+                               xen_max_p2m_pfn = pfn_s + n_pfns;
                        } else
                                type = E820_UNUSABLE;
                }

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index bf4a23c7c5918f6849e764a8376c3608cc591933..1fa633b2d556e6a33a86779fb5d711e19f13839c 100644 (file)
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -638,9 +638,9 @@ static int __init balloon_init(void)
         * regions (see arch/x86/xen/setup.c).
         */
        for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++)
-               if (xen_extra_mem[i].size)
-                       balloon_add_region(PFN_UP(xen_extra_mem[i].start),
-                                          PFN_DOWN(xen_extra_mem[i].size));
+               if (xen_extra_mem[i].n_pfns)
+                       balloon_add_region(xen_extra_mem[i].start_pfn,
+                                          xen_extra_mem[i].n_pfns);
 
        return 0;
 }

diff --git a/include/xen/page.h b/include/xen/page.h
index c5ed20bb3fe96d5f309c5299a55a7ba3b7a140bd..a5983da2f5cd929e8461eb25814c3a26ebc8e15e 100644 (file)
--- a/include/xen/page.h
+++ b/include/xen/page.h
@@ -9,8 +9,8 @@ static inline unsigned long page_to_mfn(struct page *page)
 }
 
 struct xen_memory_region {
-       phys_addr_t start;
-       phys_addr_t size;
+       unsigned long start_pfn;
+       unsigned long n_pfns;
 };
 
 #define XEN_EXTRA_MEM_MAX_REGIONS 128 /* == E820MAX */